E3 and Burst shooting

OK, I'm a Canon user or have been until this month when I acquired an E3 and a couple of lenses after being blown away by the sheer quality of the images that can be produced by an Olympus camera and lenses.

I took the E3 along with a 50-200mm f2.8-3.5 ED SWD Lens and my Canon Eos 1D MkIIn and the Canon 70 - 200mm f2.8 to a hunter trial at the weekend to try out the E3 on my main work which is show jumping and other equestrian events.

The Olympus was set at high burst rate and C-AF ... it could not keep up with the horses almost every shot was blurred. I changed settings to High burst and S-AF .. a little better but sometimes the camera would not even focus. The Canon ... no problem and the light was excellent.

Before I seriously think about buying the Olympus 35-100mm f2.0 can anyone tell me is this normal for the E3 or am I doing something wrong?